Inhibition of Eimeria tenella replication after recombinant IFN-gamma activation in chicken macrophages, fibroblasts and epithelial cells

We have previously shown that activation of primary cultures of chicken bone-marrow macrophages and embryo fibroblasts with supernatants of concanavaline A-stimulated or reticuloendotheliosis virus (REV)-transformed chicken spleen cells as source of IFN-gamma significantly decreases Eimeria tenella growth in vitro. In the present study, we used various chicken cell lines, HD11 macrophages and DU24 fibroblasts, both virally transformed, CHCC-OU2 fibroblasts and LMH hepatic epithelial cells, both chemically transformed, to replicate E. tenella in vitro. We confirmed the previous results by showing that HD11 macrophages pre-treated for 24h with recombinant chicken IFN-gamma (either produced in E. coli or by transfected COS cells), at doses ranging from 1000 to 10U/ml, drastically inhibited E. tenella replication as measured by 3H] uracil uptake after a further 70h of culture, as when treated with REV supernatant. Likewise the fibroblast and epithelial cell lines exhibited significant inhibitory activity on E. tenella replication after pre-treatment with recombinant chicken IFN-gamma, but were less sensitive (1000-100U/ml) than when treated with REV supernatant. Recombinant chicken IFN-alpha pre-treatment of all cell lines had no inhibitory effect on parasite development.